The top improvers since 2011 have been Ivory Coast (35th place, up 8.5 points to 48.3), Zimbabwe (44th, up 4.6 to 40.4) and Senegal (ninth, up 4.5 to 62.4).

Meanwhile the worst fallers were South Sudan (down 9.6), the Central African Republic (down 8.4) and Mali (30th, down 8.1 to 48.7).

"The quality of governance in Africa that had increased quite nicely until four or five years ago has stalled. This is a worrying development," Pascal Lamy, former director-general of the World Trade Organization, told AFP.

"Countries who have stronger institutions which are less corrupt and have free and fair elections are doing better economically and socially."

Abdoulie Janneh, a Mo Ibrahim Foundation board member and a former UN official, said Africa was generally on track to improving both its governance and its economic situation but progress had stalled.

"This is a wake-up call," he told AFP.

Ibrahim began compiling the index in 2006 in a bid to help countries measure and improve their performance.